[akke]

I've checked vbulletin's code and I'm pretty sure this can be done without template changes or changes to the original vbulletin code. There seem to be enough hooks to do this from the plugin system. That's nice but I'm not 100% sure yet as I've not been able to look further because I'm actually busy doing other things.
If you want me to write a mod like this for vb4, then please contact me. I'm accepting donation that will allow me to make time for writing a PM Attachments mod for vb4.

edit: a template change is needed (you need to add the {vb:raw attachmentoption} below the editor.)